superlative degree

Short definition from Wiktionary

Noun

1. 1
   The degree of comparison of an adjective or adverb used when comparing three or more entities in terms of a certain property or a certain way of doing something. In English, the superlative of superiority is formed by adding the suffix -est or the word most (e.g. biggest, most fully); the superlative of inferiority, by adding the word least (e.g. least big, least fully).